Novashell is a high-level 2D game maker that tries to handle all the hard work behind the scenes allowing you to whip up sweet games using path finding, dialog, persistent dynamically sized maps with construction/deconstruction, save anywhere, and especially features that adventure and RPG type games would use. It's also built to allow easy sharing of games you make and modding of them. The underlying concept is everything is cut and pastable and can be added and removed even during play.
The worlds/games/mods it makes can be played under Windows, OS X, and Linux without changes.
Free to use and distribute stand-alone games.
Open source under a zlib/libpng license.